The present invention relates to an interlocking device for low-voltage automatic circuit breakers, i.e., having operating voltages of up to approximately 1000 volts, with improved functions and characteristics.
Generally, low-voltage industrial electrical systems in which high-value currents, and therefore high power levels, are involved normally use specific devices, commonly known in the art as automatic or power circuit breakers. Said circuit breakers typically operate with DC or AC currents whose nominal value, depending on the applications, can vary over a wide range, typically from fractions of an ampere to several thousand amperes, and are conceived so as to provide a series of basic performance features in order to ensure the correct operation of the electrical system in which they are inserted and of the loads connected thereto.
In particular, they protect the loads from abnormal events caused by short-circuit faults or due to overloads by automatically opening the power supply circuit; they allow the correct insertion/disconnection of loads in/from the circuit; they ensure that the nominal current for the various connected users is truly equal to the required current; they allow, by manual intervention on a lever for the actuation of said circuit breaker and the corresponding separation of the movable contacts from the fixed contacts, the complete isolation of a load with respect to a power source and the consequent disconnection of the circuit that said circuit breakers protect.
In many practical applications, for example in use in automated industrial electrical systems, circuit breakers are required to perform additional functions that are auxiliary with respect to the basic ones that they normally perform; for this purpose, they are equipped with appropriate accessory devices that vary according to the type of auxiliary function to be performed.
One auxiliary function that is typically required in certain practical applications is known in the art as interlocking of two or more circuit breakers; this function is used when there are two or more electric circuits that operate in parallel to each other and cannot be closed simultaneously. For example, in the case of two electric circuits, the open condition of one of the two circuits while the other one is closed is maintained by acting manually on an appropriate interlocking device that is operatively associated with two circuit breakers, each inserted in the corresponding circuit; this device acts on the opening/closure mechanism of the circuit breaker associated with the circuit that must remain open and prevents any further movement thereof until further operator intervention occurs.
In the current state of the art, interlocking devices of the known type, despite adequately providing the required functional performance, have drawbacks and disadvantages.
In particular, a significant drawback of interlocking devices of the known art is the fact that in their typical form of application they are installed by fixing them directly to the front part or sides of the circuit breakers associated therewith. With this solution, it is therefore necessary to perforate, or even disassemble, the body of the circuit breakers and connect the device to the circuit breakers by using fixing means such as screws or pins that pass through the body of the circuit breakers and mate with them. This entails increased involvement and operating difficulties for workers, with a negative impact in terms of times and costs; moreover, the operations for perforation and for insertion of the fixing means can damage the circuit breakers and in any case entail a deterioration of active and/or structural parts during the useful lifetime of said circuit breakers. Moreover, with this conventional solution the means for fixing the interlocking device to the circuit breakers can be accessed directly even when one of the circuit breakers is closed; in this case, therefore, an inappropriate intervention on the part of an operator might lead to tampering with the interlocking device, with negative consequences as regards general safety conditions.
Moreover, solutions are known in the art in which at least one of the components of the interlocking device is fixed to the mounting plate on the opposite side with respect to the side on which the circuit breakers are mounted; these solutions entail an increase in volume and space occupation requirements and in any case generally require the use of components that pass through the body of the circuit breakers and interact with their mechanisms.
Finally, at least some of the known types of interlocking device cannot be used with circuit breakers having mutually different sizes.
The aim of the present invention is to provide a device for interlocking at least two circuit breakers that allows to obviate the drawbacks of the known art and in particular can be installed in a simplified manner and at the same time provides improved functional performance with respect to devices of the known type.
Within this aim, an object of the present invention is to provide a device for interlocking at least two circuit breakers that allows to avoid, during installation, interventions on the body of said circuit breakers, so as to prevent any damage thereto and/or avoid contributing, during their useful lifetime, to degradation of active and/or structural parts thereof.
Another object of the present invention is to provide a device for interlocking at least two circuit breakers that has, with respect to devices of the known type, a structure that is more compact and can also be used with circuit breakers of different sizes.
Another object of the present invention is to provide a device for interlocking at least two circuit breakers that allows to improve the general safety conditions of the entire electrical system in which it is used, eliminating completely or at least minimizing the possibilities of tampering, particularly when one of the circuit breakers is in the closed position.
Another object of the present invention is to provide a device for interlocking at least two circuit breakers that allows to reduce the difficulties and involvement faced by installation engineers, with a consequent benefit in terms of times and costs.
Another object of the present invention is to provide a device for interlocking at least two circuit breakers that is highly reliable, relatively easy to manufacture and at competitive costs.
This aim and these and other objects that will become better apparent hereinafter are achieved by a device for interlocking at least two single- or multipole circuit breakers, of which:
a first circuit breaker having an enclosure that contains, for each pole, at least one fixed contact and one movable contact that can be operatively coupled/uncoupled with respect to each other, actuation means suitable to provide the energy required to move the movable contacts, and a first opening/closure lever that protrudes outside said enclosure;
a second circuit breaker having an enclosure that contains, for each pole, at least one fixed contact and one movable contact that can be operatively coupled/uncoupled with respect to each other, actuation means suitable to provide the energy required to move the movable contacts, and a second opening/closure lever that protrudes outside said enclosure;
characterized in that it comprises at least:
a first supporting bracket, suitable to be fixed to a mounting plate of said first and second circuit breakers;
a second bracket, suitable to be fixed by virtue of fixing means to said first bracket and to be supported thereby;
an interlocking element, provided with a contoured body that is operatively coupled to said second bracket so that it can move with respect to it, said interlocking element being suitable to be rigidly connected to the second bracket, by virtue of locking means, in a chosen position in which it interacts operatively with at least said first opening/closure lever in a condition that corresponds to the opening of the first circuit breaker, preventing its movement and preventing the circuit breakers from being closed simultaneously.
In this manner, one has the advantage that the interlocking device according to the invention is mounted directly on the mounting plate of the circuit breakers and allows to lock at least one of them in the open position, by acting on the opening/closure lever and therefore externally with respect to the enclosure, without having to perforate or disassemble the body of the circuit breakers.